preempt vs pre-emptive

preempt is a noun but pre-emptive is not a noun.

Word	Noun	Adjective	Verb	Adverb
preempt	Yes	No	Yes	No
pre-emptive	No	Yes	No	No

preempt (noun)	pre-emptive (noun)
a high bid that is intended to prevent the opposing players from bidding

preempt (adjective)	pre-emptive (adjective)
	designed or having the power to deter or prevent an anticipated situation or occurrence

preempt (verb)	pre-emptive (verb)
acquire for oneself before others can do so
make a preemptive bid in the game of bridge
gain possession of by prior right or opportunity, especially so as to obtain the right to buy (land)
take the place of or have precedence over